Abstract
The influence of implantation of cerium on the corrosion behavior of an 32Ni-20Cr austenitic steel, Alloy 800H, in a simulated coal-gasification atmosphere has been examined at 700°C. The composition and microstructure of the corrosion products formed after exposure periods between 1 min and 200 h were examined with a range of surface-analytical techniques. The corrosion mechanism of Alloy 800H was characterized as a mixture of oxidation and sulphidation, primarily of Cr and Fe. The oxides provided protection against catastrophic sulphidation. Cerium implantation reduced the corrosive attack, providing the dose was sufficient. The corrosion was more uniform and the products had a higher Cr/Fe ratio compared to those on the unimplanted alloy. It is proposed that these changes resulted from the formation of a more protective and more stable oxide layer, due to the rapid formation of ceria particles, specifically hindering the formation of the less-stable oxides and sulphides.
Published Version
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